Help! APC 1500 Smart UPS went up in SMOKE!

[thekidkevin93]

I was careless, it's on me. I was tidying up my external battery bank I had wired into a black APC Smart 1500 UPS, upgrading the end of the extension wire with proper lugs,
the cabinet with the giant 12v wheelchair/mobility scooter FLA batteries was dark, I run the UPS on this 24v bank, I hadn't had my morning coffee, I just wanted to get it over with and start my day....my blind ass hooked up the lines BACKWARDS. from the UPS: BOOOOOM!........SMOKE.........beep-beep-beep.

After a lot of mother F's and GD's and holy S's! I sucked down some coffee, and opened up the UPS to see the damage I did. Exploded all 8 STP140NF55 MOSFETS, three 25v 330MF caps near the heatsink are bulged. On the underside a thin trace got hot enough (but not burnt) to shed its coating and reveal copper.

24v cooling fan is OK.

I looked on ebay, no replacement boards, called the local college looking to buy decommissioned UPS hardware, in the age after the year 2010 even if you offer money, liability, red tape, bluh bluh bluh,
they wouldn't play ball. Looked up the MOSFETS on digikey and Mouser....out of stock until 2024.

I remember back in 2010 living in another town, I bought two Dell Pentium III Xeon servers from the local college and they bright it to my home in a truck. $80. The deal was, $60 for one or pay $80 and I get two. Yeah you read it right. Those were the days.

This thing is my primary battery backup here in my home, my backup UPS to my primary is a black APC Smart 1000 UPS.

Guys, what do I do? what damage have I done to stupidly hook this up backwards? What other components have I fried? Should I try to replace what things I can see and hope thats all that fried?

What is a proper substitute for the (80A?) STP140NF55? I get conflicting opinions.....one site even spit at me a number for a MOSFET that was thirty Amps! For a MOSFET that is 80 Amps!???

Help help help! Please!

[bdunham7]

Guys, what do I do? what damage have I done to stupidly hook this up backwards? What other components have I fried? Should I try to replace what things I can see and hope thats all that fried?

If you take it apart and inspect the circuit board closely you are likely going to find all sorts of other small components and even circuit traces that have been burned, exploded and so forth.  These are simply not protected against shorting or reverse polarity.  I know this from experience...

Your best solution is to fire up eBay and start looking for someone selling one cheap without batteries.  What exact model is yours?  I just acquired an SMT1500 w/o batteries, sold "as is for parts" for $49 shipped.  I installed batteries and it seems to be working fine.  I can't guarantee you'll find that good of a deal, especially in Canada, but I can promise you that any APC SmartUPS that has blown main power MOSFETs is going to look very ugly when you have a closer look.

[thekidkevin93]

UPDATE: I removed all four heatsinks, desoldered all eight blown MOSFETS, and desoldered all three of the blown 330mF caps.
I had to use my Weller model 8200 gun (old school model 8200, not the newer crappier one with the same model number) to take the heatsinks off,
I had to DRILL OUT all the torx screws holding each MOSFET in. No idea why they were seized and turned so slowly than blam they stripped, but I drilled all of them out.
Than I used my temperature controlled soldering iron at 370 oC to remove the fried MOSFETS.

[thekidkevin93]

It is a model SMT1500 AS1027121495. It's a black case standalone model (non rack type). It's made by APC and its a smart UPS, which after what I did to it this morning;
I think its probably a lot smarter than I am.

That's the first thing I looked for was an APC 1500 with no batteries. I saw similar models for BIG money, than I looked for just the PCB, no results. Now I'm willing to try to replace the compoents and try to fix what I got. Now here I am with my hat in hand.

[Algoma]

I did just tear apart a old SMT1500 for recycling, Most of its gone, but I only keet a few of the more useful ICs from the board. And kept the transformer for scrap copper.  There are many differnt model years.

That whole PCB is unlikely to ever be reliable again considering how much feedback and monitoring is within a SmartUPS compared to APC's BackUPS products, any bits out of tolerance and that controller is designed always refuse to output any power (Beeping Alarm).. Given APC used to have a quarter million connected equipment coverage guarentee on those units when they're new.

I've got a few of the chips from one (OpAmps / PWM controller .. etc), but repair is likely not practical.

[thekidkevin93]

I washed off the soot and it was just smoke residue  around the mosfets. I brushed it away with a toothbrush and mild cleaner and discovered another trace that got hot and shed its coating.

[bdunham7]

That's the first thing I looked for was an APC 1500 with no batteries. I saw similar models for BIG money, than I looked for just the PCB, no results. Now I'm willing to try to replace the compoents and try to fix what I got. Now here I am with my hat in hand.

I'm seeing complete units for ~$175 USD and circuit boards for ~$80, of course in Canada and CAD it will likely be more.  To get a deal like I did you'll have to stalk eBay for awhile, most sellers know what their stuff is worth.

If you want to fix it, perhaps take some high-resolution pictures of both sides of your circuit board and let us have a look.  If you have trouble posting photos just ask for help, the forum is a bit tricky with attached files and posting external photo links has other downsides. 

[thekidkevin93]

The million dollar question gents is: what is an appropriate substitute for the eight  55v 80A P140NF55 MOSFETS I fried?
Something Digikey or Mouser have on hand right NOW and isn't $30 a piece. Obviously I want to get a ten piece tube of these MOSFETS.

[thekidkevin93]

The million dollar question gents is: what is an appropriate substitute for the eight  55v 80A P140NF55 MOSFETS I fried?
Something Digikey or Mouser have on hand right NOW and isn't $30 a piece. Obviously I want to get a ten piece tube of these MOSFETS.

OK i'm new here so i'm figuring out how I can share photos but I will take some hi res photos and figure out later how to send them.

[bdunham7]

https://www.mouser.com/datasheet/2/196/Infineon_IRF1405Z_DataSheet_v01_01_EN-3165877.pdf

[thekidkevin93]

OK I couldn't find my good Canon digital camera, so here are some photos I took with my 2012 phone.

https://ibb.co/cxDhjSr
https://ibb.co/Q9rjXdn
https://ibb.co/L8ghTD6
https://ibb.co/9HZ9rZz
https://ibb.co/nPy2WxH
https://ibb.co/vdXTgcT

[thekidkevin93]

For ten IRF1405ZPBF MOSFETs Mouser wants $54.60 total....... They want $20 to ship ten little transistors.

Somebody put me back in the fridge.

Update: Digikey wants $35 CAN for 8x MOSFETS and 3x 330 mF 35v caps. Thats more reasonable....wait shipping.....$8.000 yeah that figures.....grand total $47.74 dollary-doos.

Wow.

[bdunham7]

I'm not sure what your price expectations are based on, but if you must go cheap just try eBay.

https://www.ebay.com/itm/303945085787

I can't see anything else obviously blown up in your photos, but I still wouldn't give particularly good odds that a new set of MOSFETs will revive it.

[Algoma]

There is a very good chance as those mosfet's body diode melted internally some of the voltage could have fed back through the gates a blew out the driver chips / pwm controller too.

[thekidkevin93]

I'm not sure what your price expectations are based on, but if you must go cheap just try eBay.

https://www.ebay.com/itm/303945085787

I can't see anything else obviously blown up in your photos, but I still wouldn't give particularly good odds that a new set of MOSFETs will revive it.

I'm not trying to be a tight wad here, but $35 for some MOSFETS and $20 to ship it is moon talk. The link you posted leads to exactly what I hoped for but vvvrrrrpppp.....Does not ship to Canada.
What, my moneys not good here?

[thekidkevin93]

I'm not sure what your price expectations are based on, but if you must go cheap just try eBay.

https://www.ebay.com/itm/303945085787

I can't see anything else obviously blown up in your photos, but I still wouldn't give particularly good odds that a new set of MOSFETs will revive it.

I'm not trying to be a tight wad here, but $35 for some MOSFETS and $20 to ship it is moon talk. The link you posted leads to exactly what I hoped for but vvvrrrrpppp.....Does not ship to Canada.
What, my moneys not good here?

Yes and I doubt that it would be visible to the naked eye. I don't know what to do.

[Algoma]

Test for short circuts to ground now that you've got the dammaged parts out..  low resistances between various chips VCC and GND.

Diode test on a multimeter and test for expected values across various diodes and fets. its a pretty short path between the battery terminals, so dammage wouldn't have spread far with only 24V, likely the drivers could withstand that voltage level by design, there looks to be plenty of protection diodes around them.

[thekidkevin93]

I find it fascinating that not one of these MOSFETS had any thermal paste on them. ZERO.

[thekidkevin93]

It was only hooked up for a few seconds but there is a chance the chips and such survived while the MOSFETS and the electrolytics nearby melted down.
I don't know. $50 for some MOSFETS , than replace them, and its possible they can all fry up because the MOSFET driver stage is bad.

[thekidkevin93]

Man I feel bad. And I feel ashamed. This thing worked like a champ since 2009 and I got it last year from a scrap yard. It worked like a champ all the time I owned it.
And in one moment of carelessness I blew it all up. I should have known better.
I have strong feeling that this is going to turn out to be an expensive lesson if I want to get the same or similar spec hardware to replace the one I nuked.

[Algoma]

All the gates had resistors on them, Worst case is IC18 or IC19 took a hit. but likely the resistors protected them.

I have those chips  (salvaged) if needed.. Digikey has them too.  Looks repairable so far, you've done well cleaning it up.

[thekidkevin93]

All the gates had resistors on them, Worst case is IC18 or IC19 took a hit. but likely the resistors protected them.

I have those chips  (salvaged) if needed.. Digikey has them too.  Looks repairable so far, you've done well cleaning it up.

Thanks, I've never removed MOSFETS before or did a damage control on a PCB before. If you salvaged a bunch a these kind of MOSFETS, what you like for eight or ten of them?
I live in Belleville.

[Algoma]

They're actuall in there with Hex screws (small allen's key) through the hollow center. I only kept a few (3) because many were dammaged upon removal and I didn't need a drawer full of used mosfets, Just a good variety of known working ones.

[bdunham7]

All the gates had resistors on them, Worst case is IC18 or IC19 took a hit. but likely the resistors protected them.

I'm not up on the detailed internal architecture of these, but they can be cold-booted from battery so the onboard control electronics has to run from 24V somehow.  Is that all protected somehow from reverse polarity?  I have a blown up SUA1000 board here that has obvious additional damage beyond the MOSFETs, including a few SOIC8 packages with their tops blown.

Also, perhaps he could test it with the MOSFETs out?  (I'm not sure, but if anyone knows...)  If the display and control work maybe has a chance.

[Algoma]

Yes there appears to be a battery tap through that F1 Fuse.  (Check if that is blown).. any dammage downstream would have blown that fuse.

There appears to be a reverse protection diode there.  (D45)

But Q45 and Q46A would be ones to check if they survived.